The Company exceeded all regulatory capital requirements with a total risk-based capital ratio of 13.0%, a Tier 1 leverage capital ratio of 8.9%, and a CET1 ratio of 9.7% at March 31, 2023.
Credit Quality
The allowance for credit losses on loans (“ACLL”) at March 31, 2023, increased to $29.9 million, or 1.29% of gross loans receivable, excluding loans HFS, compared to $28.0 million, or 1.26% of gross loans receivable, excluding loans HFS at December 31, 2022, and $23.4 million, or 1.28% of gross loans receivable, excluding loans HFS, at March 31, 2022. The $1.9 million increase in the ACLL was primarily due to higher risks from economic uncertainty, the increase in loans, and increased reserves on individually evaluated nonaccrual loans. The $6.6 million increase in the ACLL at March 31, 2023, from March 31, 2022, was primarily due to the growth in loans. The allowance for credit losses on unfunded loan commitments decreased $249,000 to $2.3 million at March 31, 2023, compared to $2.5 million at December 31, 2022, and decreased $804,000 from $3.1 million at March 31, 2022.
Nonperforming loans were unchanged at $8.7 million for both March 31, 2023 and December 31, 2022, and increased $1.9 million from $6.8 million at March 31, 2022. The year over year increase in nonperforming loans was primarily due to an increase in nonperforming commercial business loans of $1.1 million, indirect home improvement loans of $750,000, and marine loans of $352,000, partially offset by decreases in nonperforming home equity loans of $212,000 and one-to-four-family loans of $104,000.
Loans classified as substandard decreased $582,000 to $19.6 million at March 31, 2023, compared to $20.2 million at December 31, 2022, and increased $6.5 million from $13.1 million at March 31, 2022. The quarter over linked quarter decrease in substandard loans was primarily attributable to decreases of $593,000 in commercial real estate loans and $335,000 in one-to-four-family loans, partially offset by increases of $198,000 in indirect home improvement loans and $142,000 in marine loans. The year over year increase in substandard loans was primarily due to increases of $4.8 million in commercial real estate loans, $1.8 million in one-to-four-family loans, $748,000 in indirect home improvement loans, and $352,000 in marine loans, partially offset by a decrease of $1.0 million in commercial and industrial loans and $215,000 in home equity loans. There was one other real estate owned property (a closed branch in Centralia) in the amount of $570,000 at both March 31, 2023 and December 31, 2022, compared to none at March 31, 2022.
Operating Results
Net interest income increased $7.9 million, to $30.7 million for the three months ended March 31, 2023, from $22.7 million for the three months ended March 31, 2022. The increase was primarily the result of an increase in loans and variable rate interest-earning assets repricing higher following recent increases in market interest rates. Interest income for the three months ended March 31, 2023, increased $14.0 million compared to the same period last year, primarily due to an increase of $12.9 million in interest income on loans receivable, including fees, impacted primarily by loan growth and rising interest rates. For the three months ended March 31, 2023, interest expense increased $6.0 million, primarily as a result of higher market interest rates.
NIM increased 46 basis points to 4.70% for the three months ended March 31, 2023, from 4.24% for the same period in the prior year. The increase in NIM reflects new loan originations at higher market interest rates, variable rate interest-earning assets repricing higher following recent increases in market interest rates. The benefit from higher rates and interest earning assets were partially offset by rising deposit and borrowing costs. Increases in average balances of higher costing CDs and borrowings placed additional pressure on the NIM.